44 research outputs found
Seed germination and seedling establishment of Cherimoya (Annona Cherimola mill.) at different temperatures
Cherimoya (Annona cherimola Mill.) has an exceptional flavor and aroma, which makes it a fruit with great potential. However, little is known about its propagation by seeds. According to the scientific literature, the germination of cherimoya seeds is affected much more by external conditions than by internal conditions. Germination of cherimoya
variety ‘Concha Lisa’ were tested for germination at constant temperatures of 25, 30, 40°C, and at room temperature, varying from 20-25°C, coupled with total darkness. Seeds were sown in Petri dishes (0.8% agar water), for 25 days of incubation. The kinetics of germination was determined according to five closely related parameters, viz. final germination percentage (FGP), mean germination time (MGT), coefficient of velocity of
germination (CVG), time to 50% germination (T50) and seedling length (SL). The temperature of 30°C was found optimally suitable with 70.8% FGP, 17.5 days MGT and 3.91 cm SL, while the room temperature of 20-25°C slightly improved germination with only 25% FGP. Furthermore, significant decrease in FGP and SL was observed at
25°C and 40°C of temperature in comparison to 30°C. The analysis also revealed that cherimoya seed germination, day 10-15 after seed sowing is suitable for final counts. An overview on the emergence of cherimoya seedlings, during a 12-week period in pots is presented
Morphological characteristics and seed germination improvement of two ecotypes of Astragalus armatus Willd. subsp. armatus in Algeria
Astragalus armatus Willd.
subsp. armatus is an endemic shrub of the
Northern Africa. Its cultivation and
domestication are very limited because of
difficulty with seed germination and
establishment. In this study, we investigated
some plant morphological characteristics
in real time and in situ (leaves, fruit
and seeds) of different ecotypes of
A. armatus, collected from two sites in
Algeria (Arid Steppe of Aïn Naga and
Condorcet Mountain), which elevation
and climate data are very different.
Moreover, the role played by the seed
coat in seed dormancy of these two
different populations was tested by the
effects of the pretreatment and its duration
on the performance of seed germination,
by considering the final germination
percentage (FGP) and the mean germination
time (MGT). These parameters are
estimated for 10 days in Petri dishes and
stored in darkness at (25°C). Pre-sowing
treatments included immersion in
concentrated sulphuric acid for 30, 60 and
90 min, and immersion in hot water
(100°C) for 10 min. Statistical analysis
showed that the treatment and the ecotypes
effects on both FGP and MGT were
highly significant (p< 0.0001). Untreated
seeds of both ecotypes of A. armatus
failed to germinate (except for a few of
Condorcet Mountain ecotypes). For both
populations, the most effective treatment
was immersion in sulphuric acid for
60 min for the ecotype of Arid Steppe of
Aïn Naga, and only 30 min for Condorcet
Mountain. An excellent germinative
strength is characterized by a higher FGP
and a reduced MGT. The morphological
characteristic and seed germination could
be attributed to intraspecific variations
resulting from the natural selection of the
same species
Effect of cold stratification on seed germination of the multipurpose fruit shrub, Ziziphus Lotus (L.) Lam. (Rhamnaceae)
Shrubs and trees of the genus Ziziphus are a good example of naturally occurring multipurpose plant species with great potential in arid regions. This study was conducted to investigate the effect of cold stratification on seed germination and seedling growth of Ziziphus lotus (L.) Lam. Seeds were subjected to 0, 45, 90 and 120 days of cold stratification at 5°C. We also examined fruit, kernel and seed morphology. For each treatment period, four replicates of 50 seeds were incubated in plastic containers between two layers of moist sand at 15% and under greenhouse conditions for 15-day period.
At the end of the experiment, the final germination percentage (FGP), shoot length and root length were assessed. The results clearly indicated that increasing duration of cold stratification improved seed germination. The most effective stratification period was 120 days where Z. lotus recorded 83% of FGP and 16.5 cm of total seedling length. Cold
stratification treatments significantly increased shoot height, root length, as well as seedling total length. 120 days stratification treatment resulted in the highest shoot and root length (6.80 cm and 9.75 cm, respectively). An overview on the emergence of Z. lotus seedlings during a 15-day period was also illustrated
Seed germination and radicle establishment related to type and level of salt in common bean (Phaseolus Vulgaris L. Var. Djedida)
Saline soils contain multiple
types of salt, each of them may exert a
different effect on seed germination and
seedling growth. The aim of this study is
to assess the effects of five types of salt
on the seed germination and radicle
establishment of common bean
(Phaseolus vulgaris L. var. Djedida).
The experiment was set out as a factorial
experiment based on completely
randomized design with four replications
of ten seeds for the seed germination and
twelve replicates for the seedling growth.
We used five kinds of salts (NaCl,
Na2SO4, CaCl2, CaCO3 and KCl) with
concentrations of 0, 100, 200 and 300 mM.
Seeds were incubated in Petri dishes at
25°C, in the dark, for 10 days. The results
of analysis of variance indicated that the
effects of salt types and concentrations,
and their interaction effect were
significant in all measured traits (P< 0.01).
However, no significance effect was
found on secondary roots number and
seedlings dry biomass with CaCO3
treatment solution. According to the
results, the inhibitory effects of the five
salt types differed significantly. Indeed,
germination of common bean seeds by
various salts were in the order of NaCl >
KCl > CaCO3 > Na2SO4 > CaCl2.
However, the taproot length, the number
of secondary roots and the seedlings dry
weight by various salts were in the order
of CaCO3 > KCl > NaCl > CaCl2 >
Na2SO4. The effect of salt concentration
was also obvious. The reduction in dry
biomass of cotyledons is proportional to
germination rates and to the development
of seedlings in dry biomass and in size.
Seeds of P. vulgaris var. Djedida were
able to germinate under all concentrations
of the various types of salt. The lowest
final germination percentage (FGP) was
obtained under 300 mM of all salts
recording the following values: CaCO3 -
60%, NaCl - 60%, KCl - 52.5%, Na2SO4 -
50% and CaCl2 - 27.5%. During germination stage, the radicle emergence
would be controlled by the environment
osmolarity, while the later growth of the
seedling would be limited by the reserve
mobilization
Seed germination and morphophysiological characterization of three tomato (Lycopersicon Esculentum) varieties irrigated with treated wastewater
The ability to reuse treated
wastewater (TWW) would be of
significant benefit to agriculture whilst at
the same time providing a valuable water
resource. This study concerned the effects
of three various levels of treated
wastewater (0%, 50% and 100% TWW)
on seed germination and plant
development of three different varieties of
tomato (Lycopersicon esculentum) (viz.
Toufan, Heinz and Bouzina). Irrigation
with TWW persisted 15 days for the
germination stage and 120 days for the
growth and development stage. A control
plot irrigated with a pure water
(groundwater) was also set up in order to
compare the seeds and the plants response
to different concentrations of irrigation
water. The final germination was
expressed as a percentage of the total
number of seeds in each treatment. This
study has demonstrated that treated
wastewater improves the germination in
Heinz variety and had no effect on both
Toufan and Bouzina varieties whether it is
pure or diluted by half. For the growth
stage, the statistical analysis showed that
the Toufan variety has tolerated
successfully the TWW irrigation with its
high and moderate concentrations, and
this by analysing all the morphophysiological
parameters studied in this
work (leaves numbers, stem and root
length and dry biomass, relative water
content and rate water loss)
Effect of nitrogen fertilizer on growth, flowering, fruiting and nodulation of three varieties of common bean in the arid region of aïn naga (Biskra, Algeria)
Field experiments were conducted to investigate the response of common bean (Phaseolus vulgaris L.) to nitrogen fertilizer. The main factor included the fertilizer (Granular Urea 46% N), was made up of two levels: no fertilization (0 kg/plot: control) and
fertilization (0.4 kg/plot), while the secondary factor was the variety (three varieties of common bean: Djedida, Nelson and Jalila). The experimental design was a randomized complete block design with split plot arrangement and replicated four times. The effect of
fertilization was evaluated during two development stages (flowering and fruiting) for each variety and this on the total dry biomass, the length of the aerial and root parts, as well as on the number of secondary roots. On the other hand, the combined effect of fertilization and variety was studied on some yield parameters per plant, such as the number of flowers, pods, seeds and the harvest index. In addition, the number of nodules at the end of seed maturation was evaluated. The results indicated that the nitrogen fertilizer application significantly reduced the root length, the number of nodules and secondary roots in most of the common bean varieties. However, fertilizer application significantly
increased dry matter in both flowering and fruiting stages, for the three studied
varieties. Pod number per plant and seed yield was increased by the application of
N fertilizer, depending on varieties and the parameters being measured. Djedida and Jalila varieties gave the best yield and can therefore be recommended to farmers. According to our results, the percentage of improvement by N fertilization on one parameter or another
does not exceed an average of 20%, compared to the control. Indeed, the effect of fertilization is positive and seems to increase the harvest index by 18% in Djedida and by 20% in Jalila, compared to non-fertilized plants. Unfertilized plants of the variety Nelson showed the highest ability to nodulate
Observer-based stabilisation of linear systems with parameter uncertainties by using enhanced LMI conditions
International audienceThis paper deals with the problem of observer-based stabilisation for linear systems with structured norm-bounded parameter uncertainties. A new design methodology is established thanks to a judicious use of some mathematical artefacts such as the well-known Young inequality and various matrix decompositions. The proposed method allows one to compute simultaneously the observer and controller gains by solving a single bilinear matrix inequality (BMI), which becomes a linear matrix inequality (LMI) by freezing some scalars. Furthermore, we show that some existing and elegant results reported in the literature can be regarded as particular cases of the stability conditions presented here. Numerical examples and evaluations of the conservatism are provided to show the effectiveness of the proposed design methodology
Optimization of Quartz Sand Leaching Process Using Design Experiments Method (DOE)
The present study aims at investigating the Algerian quartz sand from Djelfa deposit as a potential source to produce silicon. The sand from the Djelfa deposit has a high concentration but not enough to be used as raw material for pyrometallurgy (97%) of SiO2. Therefore, the quartz was treated using acid leaching process to increase the silica concentration up to 98.5%. Otherwise, we employ Design of Experiments Method Software (DOE) as numerical model to optimize the parameters of leaching and also to predict the etching behavior of sand grains during the primary step of the process. The results show that the effect of acid concentration has more influence than the grains particle sizes and leaching time to obtain the required silica purity. Using DOE numerical method in the first step of leaching, optimal response of purity (ΔP)(ΔP)\\left (\\mathrm \\\\Delta \ P\ \\right ) about 98.48% is obtained. In this context, the optimal grain sizes of sand and the optimal acid concentration are respectively, 276.9 \textmum and 21.15%, for 6 hours leaching time. The obtained response is very close to the experimental values and can be used for the next stage of the silicon production chain
Sand Dune Characterization for Preparing Metallurgical Grade Silicon
Dune sand, from Biskra, Algeria which is in the Great Algerian huge desert attracts tourists from all over the world. Dune sand composes around 80% of the total area of the desert. To date only a few studies have been conducted on this sand. The purpose of the present study is to shed light on the textural and physico-chemical characteristics of this sand using several characterization methods, and to understand the potential for using for photovoltaic applications. The chemical composition of Biskra sand indicated a high purity quartz with 97.6% silica, and a presence of others oxides. Granular analysis enabled the determination of the size of the sand grains which was found to be fine to medium. On the other hand, a Scanning Electron Microscopy and optical observations were carried out, the micrographs observations indicated the presence of different shapes of sand grain, some rounded whereas others are angular edged or elongated. X-ray diffraction indicates the highly crystalline nature of the Biskra sand